3.07 or 3.08 in the 1/2 ton is excellent if (and only if) you are careful with the gear ratios in the T5. If you do your homework cleverly, you can have a 5 speed with the first 3 gears matching the original overall ratios in the AD truck. Important? Only if you want to use it like a truck. Then your 4th gear becomes your first "overdrive" and if you have 3.07 will drop your rpms by ~25%. If your 5th gear is .86, then you'll be good to go. If your 5th is .72, your engine will lug and you won't like it a bit.
In a 3/4 ton, my question would be the same. How do you plan to use it? If as a truck, then as Jerry said something in the 3.73 range is what I'd think would be good. But again it depends on the transmission gear ratios to a big degree. A few people told me a 3.07 rear wouldn't work, but with the gear ratios I have no driver would ever know the difference from the stock 3 speed until he hit 4th gear.
